Plant genetic engineering allows plant breeders to modify the genetic makeup of a plant precisely and predictably. Both alone and in combination with traditional plant breeding techniques, genetic engineering facilitates the creation of improved varieties faster, and with greater ease, than is possible when only traditional plant-breeding techniques are available.
Isolated plant promoters are instrumental for constructing genetically engineered plants. Typically, to produce transgenic plants, an isolated plant promoter is inserted into a vector and operably linked to a heterologous DNA sequence, thereby creating an expression construct. Plant cells are then transformed with the expression construct by any of a number of art recognized methods. The result of transformation is that the plant promoter operably linked to the heterologous DNA, is inserted into the genome of the transformed plant cell, and regulation of the heterologous DNA expression in the transformed plant cell is controlled by the promoter.
There are a variety of different approaches for producing a desired phenotype in a transgenic plant. The chosen approach typically depends on the nature of the heterologous sequences coupled to the isolated plant promoter. For example, expression of a novel gene that is not normally expressed in plant, or in a particular tissue of a plant, may confer a phenotypic change. Alternatively, the expression of a sense or an antisense construct introduced into transgenic plants can cause the inhibition of expression of endogenous plant genes. This inhibition of expression can, in turn, produce a desired phenotypic change.
Unfortunately however, promoter elements capable of directing high levels of transgene expression are difficult to isolate and relatively few promoter control elements have been demonstrated to perform well in crop plants. Thus, promoters useful for the genetic engineering of plants, particularly crop plants, remain limited in number, and as a result, there is a continuing demand for new promoters.
To facilitate the production of precise phenotypes, it is advantageous to have available a variety of different promoters for the genetic engineering of plants. Furthermore, since most of the well-characterized promoters that are currently available confer constitutive expression, novel promoters with reliable organ-specific expression in transgenic plants are needed in the art.
Fortunately, as will be clear from the following disclosure, the present invention provides for these and other needs.